Transmission Actuator

ABSTRACT

The invention relates to a transmission actuator for actuating a manual transmission in an automated manner, comprising a lane selection actuating cylinder ( 1 ) for selecting a shift lane ( 8, 9, 10, 11 ) and a gear selection actuating cylinder ( 2 ) for engaging a gear ( 12, 13, 14, 15, 16, 17, 18 ) in a shift lane ( 8, 9, 10, 11 ). Starting therefrom, a transmission actuator for actuating a manual transmission in an automated manner is specified, wherein a plurality of defined positions can are reachable with little design effort. For this purpose, the lane selection actuating cylinder ( 1 ) or a component ( 6 ) that can be moved by the lane selection actuating cylinder ( 1 ) can be automatically fixed in at least one predetermined locking position ( 19 ) by means of a locking device ( 28, 29, 30 ).

The present invention generally concerns a gearbox actuator for automatic operation of a manual gearbox according to the preamble of claim 1.

Gearbox actuators of the general type under consideration are used to automate gearboxes in manual transmissions. In such manual transmissions, it is proposed that a gear selector element, which would be operated with a gear stick on manual operation, is guided along a selection gate to a desired shift gate and then moved into a gear position in order to engage a gear. Usually several shift gates are provided along the selection gate, transverse to the selection gate. These shift gates end in positions in which a gear is engaged. FIG. 1 is a high level schematic showing, as an example, a gearbox with six forward gears and one reverse gear. Three shift gates 9, 10, 11 are provided along a selection gate 7 for forward gears and a further shift gate 8 for reverse gear.

A gearbox actuator for gearbox automation usually has an actuating cylinder via which the gear selector element is guided along the selection gate and can be positioned at an intersection point of a desired shift gate. Such an actuating cylinder is called a gate selection actuating cylinder. To engage a gear in the selected shift gate, a gear selection actuating cylinder is provided that guides the gear selection element accordingly into the selected shift gate and positions it so that the desired gear is engaged.

For precise positioning of the gear selection element in the selection gate, conventional gearbox actuators use a gate selection actuating cylinder with a number of defined shift positions corresponding to the number of shift gates, which positions can be set by activation of a pressure medium. To approach three positions, for example, a three-position cylinder is used. Such a three-position cylinder is in itself already relatively complex. For precise positioning with .a higher number of shift positions, the design complexity for a corresponding multiposition cylinder would be even greater.

It is therefore an object of the present invention to provide a gear actuator for automated operation of a manual gearbox in which, with low constructional complexity, a multiplicity of defined positions can be approached.

This object is achieved by the embodiment of the invention set forth in claim 1. The subclaims show advantageous refinements of the invention.

According to the invention it is proposed that the gate selection actuating cylinder or a component that can be moved by the gate selection actuating cylinder can be fixed automatically via a catch device in at least one predetermined catch position. Such a catch device can be provided with relatively little constructional complexity and at the same time favorable production costs. A catch device can also be implemented in existing gear actuator constructions at reasonable cost. By means of the invention it is advantageously possible to use a relatively simple actuating cylinder as a gate selection actuating cylinder, such as e.g., a double-action actuating cylinder with only two defined positions as such, namely a front and a rear end position. On activation of such an actuating cylinder with pressure medium, in particular with compressed air, it would not be possible simply to approach defined intermediate positions between the end positions. The use of the catch device proposed according to the embodiments of the invention means that fixing in one or more additionally desired intermediate positions corresponding to the catch positions between the end positions is possible at low cost.

In relation to other constructional solutions such as e.g., the provision of an additional piston in a multi-position actuating cylinder, the solution proposed according to the invention can be achieved economically and because it requires little construction space, it can easily be integrated in existing devices. In comparison with spring centering, the invention has the advantage that the necessary shift force of the actuating cylinder is not or only insignificantly increased.

The device also comprises the possibility of forming one or both end positions of the actuating cylinder as catch positions. According to an advantageous embodiment of the invention, the catch position is different from the end positions of the gate selection actuating cylinder. As a result, advantageously, an additional shift position that can be approached in a defined manner for gate selection can easily be created.

According to an embodiment of the invention, the fixing achieved by the catch device can be overcome by activation of the gate selection actuating cylinder. This has the advantage that no additional components are required for unlocking the catch device, such as a piston activated by compressed air. Fixing can be overcome by activation of the pressure medium of the gate selection actuating cylinder if this is activated with sufficiently high pressure.

According to a further embodiment of the invention, the gate selection actuating cylinder is designed to move a shift finger into a selection gate. The shift fmger serves advantageously as a gear selection element with which the corresponding gear parts can be activated to engage a gear.

According to another embodiment of the invention, the gate selection actuating cylinder is formed as a multi-position cylinder, which as well as the end positions has at least one predetermined intermediate position that can be approached by activation of the pressure medium. The gate selection actuating cylinder can in particular be formed as a three-position cylinder. The catch position here differs from the end positions and the intermediate position. As a result, with little cost a further shift position, which can be approached in a defined manner, is created without the need to further complicate the design of the gate selection actuating cylinder. Thus, with a three-position cylinder and an additional catch position, a gearbox with four shift gates can be operated automatically by the gearbox actuator.

The invention contemplates that further catch positions can be provided. As a result, the number of shift positions that can be approached in a defined manner can be increased further with little cost.

According to another embodiment of the invention, the catch device has a locking element, which in the catch position engages in an allocated locking recess. The locking element is under spring force in the direction of the locking recess. This allows a constructionally simple and low cost production of an automatically acting catch device.

According to a still further embodiment the invention, the locking recess has sloping side walls. With corresponding dimensioning of the spring force of the catch device, this advantageously allows the angle of the side walls and the profile of the locking element engaging in the locking recess to be matched to the catch device so as, firstly, to achieve secure fixing in the catch position, and, secondly, by activating the pressure medium, the fixing achieved by the catch device can be overcome by activating the pressure medium of the gate selection actuating cylinder.

According to a further embodiment of the invention, the locking element is integrated in the shift finger. This allows a favourable design and space-saving arrangement of the locking element.

According to another embodiment of the invention, the gear actuator has a distance sensor to detect the activation stroke of the gate selection actuating cylinder. By means of the distance sensor, advantageously, the activation of the gate selection actuating cylinder and the reaching of the desired shift positions can be monitored.

According to a further embodiment of the invention, the distance sensor is connected with an electronic control device. The electronic control device is designed to evaluate the distance signal of the distance sensor and output an actuating signal to the gate selection actuating cylinder. The electronic control device is furthermore designed for automatic learning of the catch position and the actuating time necessary for actuation of the gate selection activating cylinder from an end position or from the intermediate position into the catch position. This allows an advantageous self-learning function of the electronic controller of the gearbox actuator. The learning function can be provided, for example, in the form of a function in the software of the electronic control device. Via the learning function, e.g., under modified friction conditions in operation of the gearbox actuator, automatic adjustment of the necessary actuation time of the gate selection actuating cylinder required to approach a particular position can be learned and then applied. This allows, as a whole, low-maintenance operation of the gearbox actuator.

The invention is now described below with reference to exemplary embodiments and the drawings.

These show:

FIG. 1—a gearbox actuator with a manual gearbox in schematic view, and

FIG. 2—a gate selection actuating cylinder with activating elements, and

FIG. 3—a sectional view of the gearbox actuator.

In the figures the same reference numerals are used for corresponding elements.

FIG. 1 is a high level schematic depiction of a manual gearbox with four shift gates 8, 9, 10, 11 and one selection gate 7. A gear selection element 6 can be moved along the selection gate 7 and, on reaching a shift gate 8, 9, 10, 11, can be moved in the orthogonal direction into one of the positions 12, 13, 14, 15, 16, 17, 18. In these positions 12, 13, 14, 15, 16, 17, 18, a desired gear of the manual gearbox shown can be engaged. To activate the gear selection element 6 along the selection gate, a gate selection actuating cylinder 1 is provided. To activate the gate selection element 6 along a shift gate, a gear selection actuating cylinder is provided.

The gate selection actuating cylinder 1 is formed e.g., as a double-action actuating cylinder with a piston 3 and a piston rod 2. The piston rod 2 is connected with the gear selection element 6. By corresponding application of the pressure medium of the pressure medium chamber to the left or right of piston 3, the piston 3 can be moved in the actuating cylinder 1 either into the left end position 4 or into the right end position 5. In particular, compressed air can be used as the pressure medium.

FIG. 2 shows an embodiment of the gate selection actuating cylinder 1 as a three-position cylinder. The gate selection actuating cylinder 1 for this has a further piston 20 as well as the piston 3 shown in FIG. 1 that is connected with piston rod 2. The piston 3 can be moved in relation to the further piston 20. The gate selection actuating cylinder 1 at position 21 also has a shoulder that serves as a stop for the further piston 20. Between the piston 3, the further piston 20 and the housing of the gate selection actuating cylinder 1 are formed pressure medium chambers 22, 23, 24. By corresponding control of the application of the pressure medium of pressure medium chambers 22, 24, the piston rod 2 can be moved into three positions, namely into the positions corresponding to shift gates 8, 9, 11. To approach the shift gate 8, pressure medium chamber 24 is pressurized. To approach shift gate 9, pressure medium chambers 22 and 24 are pressurized. To approach shift gate 11, only pressure medium chamber 22 is pressurized. The positions corresponding to shift gates 8, 9, 10, 11 are shown in FIG. 2 in relation to the end of the piston rod 2. The pressure medium chamber 23 (middle chamber) is connected with atmospheric pressure and is not pressurized.

In order also to be able to approach shift gate 10, a catch device is provided that has a locking element 28, which is supported via a spring 30 on a housing component or other fixed component of the gearbox actuator. A catch recess is provided on the piston rod 2 that can be formed as a dip 29. When the gate selection actuating cylinder 1 is moved, for example, from shift gate 9 towards shift gate 11, the locking element 28 at a particular time meets the locking recess 29 and engages therein. If the pressure in the pressure medium chamber 22 remains sufficiently high, the piston rod is moved further in the direction towards shift gate and the fixing at the catch position is then overcome again. If the pressure medium chamber 22 is pressurized with a correspondingly short pressure pulse, which is reduced to a sufficiently low level on reaching catch position 19, an automatic fixing in catch position 19 takes place. The level to which the pressure pulse must be reduced on reaching catch position 19 to guarantee fixing is determined by the spring force of the spring 30 and by the respective contouring of the intermeshing surfaces of the locking element 28 and locking recess 29.

The gate selection actuating cylinder 1 is moved from catch position 19 into another shift position by pressurising the corresponding pressure medium chambers 22, 24. This overcomes the fixing at the catch position.

The gate selection actuating cylinder 1 has an electrically controllable actuating unit 25, which can be implemented, for example, by solenoid valves. Via actuating unit 25, the pressure medium is introduced into pressure medium chambers 22, 24 or dissipated therefrom according to the setting of an electronic control unit 27.

The actuating cylinder 1 also has a distance sensor 26 via which the stroke covered by the piston 3 or piston rod 2 can be detected. The distance sensor 26 can be formed, for example, as an inductive sensor, in particular a PLCD sensor.

The distance sensor 26 and actuating unit 25 are connected via electrical lines with the electronic control device 27. The electronic control device 27 serves to control the gearbox actuator and has a corresponding control program.

FIG. 3 is a sectional view showing the design elements of the gearbox actuator relevant for the invention. The piston rod 2 with which the gear selector element 6 is connected can be seen. The gear selection element 6 has a blocking piece 31, a shift fmger 32, a gate shift piece 35 and a gear shift piece 34. The blocking piece 31 constitutes the connection of the piston rod 2 with the gear selection element 6. The shift finger 32 is arranged inside the blocking piece 31. The gate shift piece 35 is firmly screwed to the blocking piece 31. The gate shift piece 35 serves for gate selection and is therefore movable in the selection gate direction. The gate shift piece 35 simultaneously serves as a guide element for the shift fmger 32 in the shift gate direction. The gear shift piece 34 can be shifted in the direction of the shift gates. It serves simultaneously as a guide in the selector gate direction.

The locking element 28 is arranged within the shift finger 32 in the form of a catch bolt with spring 30. The locking recess 29 is arranged in the gear shift piece 34 below the shift fmger 32 in the form of a dip. The dip 29 has a peripheral wall 33, which has a predetermined slope. The slope of the wall 33 is matched to the tip of the locking bolt 28 such that further taking into account the force of the spring 30, catch position 19 can be overcome by pressurisation of the actuating cylinder 1.

As evident from the exemplary embodiments shown in FIGS. 2 and 3, the invention allows various possibilities of advantageous arrangements of the components of the catch device in the gearbox actuator. FIG. 2 shows an example in which the locking element 28 and spring 30 are firmly arranged at a position fixed in relation to the housing, while the locking recess 29 is arranged on a movable component in relation thereto. FIG. 3 shows an example in which the locking recess 29 is arranged at a position fixed in relation to the housing while the locking element 28 and spring 30 are arranged on a movable component in relation thereto. 

1. A gearbox actuator for automatic operation of a manual gearbox with a gate selection actuating cylinder (1) for selection of a shift gate (8, 9, 10, 11) and a gear selection actuating cylinder (2) for engaging a gear (12, 13, 14, 15, 16, 17, 18) in a shift gate (8, 9, 10, 11), characterized in that the gate selection actuating cylinder (1) or a component (6) which can be moved by the gate selection actuating cylinder (1) can be fixed automatically via a catch device (28, 29, 30) in at least one predetermined catch position (19).
 2. The gearbox actuator according to claim 1, characterized in that the fixing (28, 29, 30) achieved by the catch device can be overcome by activation of pressure medium of the gate selection actuating cylinder (1).
 3. The gearbox actuator according to either of the preceding claims, characterized in that the catch position (19) differs from the end positions (4, 5) of the gate selection actuating cylinder (1).
 4. The gearbox actuator according to any of the preceding claims, characterized in that the gate selection actuating cylinder (1) is designed for moving a shift finger (6) in a selection gate (7).
 5. The gearbox actuator according to any of the preceding claims, characterized in that the gate selection actuating cylinder (1) is formed as a multiposition cylinder which in addition to the end positions (4, 5) has at least one predetermined intermediate position (21) which can be approached by activation of pressure medium, and the catch position (19) is different from the end positions (4, 5) and the intermediate position (21).
 6. The gearbox actuator according to any of the preceding claims, characterized in that the catch device (28, 29, 30) has a locking element (28) which in the catch position (19) engages in an allocated locking recess (29), and the locking element (28) is exposed to spring force in the direction of the locking recess (29).
 7. The gearbox actuator according to claim 6, characterized in that the locking recess (29) has sloping side walls (33).
 8. The gearbox actuator according to claim 6 or 7, characterized in that the locking element (28) is arranged integrated in the shift finger (6).
 9. The gearbox actuator according to any of the preceding claims, characterized in that the gearbox actuator comprises a distance sensor (26) to detect the activation stroke of the gate selection actuating cylinder (1).
 10. The gearbox actuator according to claim 9, characterized in that the distance sensor (26) is connected with an electronic control device (27) which is designed to evaluate the distance signal of the distance sensor (26) and to output an activation signal to the gate selection actuating cylinder (1), wherein the electronic control device (27) is designed for automatic learning of the catch position (19) and the activation time necessary for activating the gate selection actuating cylinder (1) from an end position (4, 5) into the catch position (19). 